Biotic factors (data)

Biotic factors are living. The community of living organisms in an ecosystem can be affected by biotic factors.

The effect of biotic factors on organisms

Red squirrels are native to Great Britain. They weigh around 300 grams, which is about half the mass of the larger grey squirrel. The grey squirrel species was introduced to England around a hundred years ago from America by wealthy landowners who wanted a fashionable addition to their forests.

The larger grey squirrel has provided competition for the native red squirrel, which has resulted in a lack of food for the red squirrel species. Organisations like the Red Squirrel Support Trust have sampled the numbers of both squirrel types over time. The results are shown below.

Organisations like the Red Squirrel Support Trust have sampled the numbers of both squirrel types over time. Their results are shown below.
Question

What conclusions can you draw from this data? [4 marks]

In 1945 grey squirrels were only found in central Southern England and in small numbers on the East coast of Northern England [1 mark]

By 2000 they had spread throughout England and Wales [1 mark]

The red squirrel is now only found in parts of Scotland and Ireland [1 mark]

The pattern does not appear to have changed much between 2000 and 2015 [1 mark]

Question

What limitations might there be in drawing these conclusions and how could these be improved? [2 marks]

This information is only from one source [1 mark]

It could be compared with others to ensure its reliability [1 mark]